1. Field of the Invention
This invention relates generally to rain gutters used on buildings having inclined roofs. In particular, to a rain gutter system that captures rain water run-off from the roof while rejecting the debris, such as leaves, pine needles, and sticks to the ground.
2. Description of Related Art
In the prior art, a gutter in the form of an open trough is used to capture the run-off from an inclined roof and divert it to down spouts. These gutters are typically about 3 inches wide and of about equal height, have a flat bottom, and are rolled ornamentally in the front. The larger debris, such as sticks, leaves, and pine needles are trapped in the gutter. The accumulation of the larger debris tends to block the flow of water at numerous locations creating settling basins for the capture of smaller particles such as decorative grit from shingles and seeds from trees; particles that would normally have been transported to ground drains in a reasonably high flow field. Gutters of conventional design and located in wooded areas eventually clog and overflow unless cleaned frequently.
Several solutions have been offered to prevent debris; from falling into, and blocking the flow in the gutter. Covers include plastic or metallic mesh, and solid plates that are slotted or perforated. These plates, or mesh, can be retro-fitted to most gutters typically used but do not prevent the pile-up of debris. Certain forms of debris, such as pine needles, tend to lodge in the apertures of the screen or perforated covers creating an untidy appearance and presenting the user with a tedious job for removal.
In a second family of designs, various solid-curved plates are placed over the gutter. The principle employed in these designs is that water has a greater adherence to the smooth-curved cover than debris, such that the water will flow around, and under, the cover and enter the gutter, while the debris, unable to follow the surface, will fall to the ground. One example of a solid cover is a design referred to as Gutter Helmet (or Gutta-Gard). The cover, flat over most of the open section of the gutter being covered, is configured with the outside edge rolled under on about a 1/2 inch radius. The cover rests on stand-offs mounted on the outside edge of the gutter making an aperture, in the form of a slot, between rolled edge of cover and the outside edge of the gutter just beneath it. The rear edge of the cover is inserted beneath a row of shingles in proximity of the edge of the roof. Pitches of from zero to approximately 15 degrees are employed for these covers with rolled outer edges. Commonly used roof pitches are 26.6 degrees(6.times.12) and 45 degrees(12.times.12). These solid covers with rolled outer edge can be retro-fitted to most gutters now in use.
Another example of a solid-cover design is the Leafguard Seamless Gutter System"(U.S. Pat. No. 4,757,649.) The design is similar to that just described except that the solid cover is an integral part of the gutter. The gutter portion of the seamless cross-section is approximately 3 inches wide. Installation involves removal of present gutters. Retention of existing downspouts is possible.
U.S. patent (U.S. Pat. Nos. 4,493,588 and 5,016,404) operate on a similar principle to the above, namely that of a curved surface to which water adheres while debris is rejected to ground level. One design (U.S. Pat. No. 5,016,404) is compatible with conventional gutter cross-sections but with non-conventional gutter installations, it being necessary to lower the gutter in order to accommodate brackets and a curved section of sheet material that encompasses the fascia board. In this design the conventional gutter is installed beneath the curved section below soffit level instead of on the face of the fascia board. The uppermost edge of the curved section is inserted beneath one of the lower rows of shingles at the roof's edge.
The design of U.S. Pat. No. 4,493,588 by Duffy resembles that of the later designs, U.S. Pat. No. 5,016,404 by Briggs except that the curved portion of the design appears to generally extend over twice the vertical height of the fascia having a bracket that extends from the bottom edge of the curved section upwards to the bottom of the soffit board. The gutter, located beneath the curved section, is dimensionally similar to conventional gutters being about 3 inches wide. A grill is added in the aperture between the curved portion and the outside edge of the gutter which the claimant includes to prevent debris from entering the gutter.
The disadvantage of the prior art, as represented by conventional gutter without a cover, is that the gutter is a nearly perfect trap for any debris carried to the edge of the roof by the flow of water; the conventional open gutter mechanically traps nearly 100 percent of debris making it necessary to manually remove this debris frequently in order to preserve functionality of the conventional gutter system.
All conventional gutters and those cited in the recent U.S. Pat. Nos. 4,493,588, 4,757,6495, and 5,016,404 trap most of the debris in the form of small particles via the principle of settling. This type of debris includes seeds from trees, pollen, and decorative grits from shingles. The technique of settling is an art well understood and, in its simplest terms involves the reduction in flow rates of the fluid in which particles of greater density than the fluid are suspended. By reducing the flow rates, the particles of greater density are given time to settle out. Conventional gutters, and those utilized in conjunction with the various covers described above, qualify in this way; featuring relatively low fluid velocity flows due to the use of relatively large-wide-flat bottom sections for the gutter. The patents of Briggs(U.S. Pat. No. 5,016,404), Duffy(U.S. Pat. No. 4,493,588), Demartini(U.S. Pat. No. 4,497,146), Bartholomew(U.S. Pat. No. 2,669,332), and Kenyon(U.S. Pat. No. 5,332,332) all require insertion of an upper flange underneath the roof cover; and in most cases fastening to attach the system to the inclined roof. All designs are at risk for causing damage to existing or new roof shingles.
The principal disadvantage of covers as depicted by Helmet Guard and Leafguard(U.S. Pat. No. 4,757,649)is that the nearly-flat portion of the covers represents a shelf having a much lower pitch than the roof to which the system is attached. The principles that govern the successful, or unsuccessful, discharge of debris from the roof include the surface roughness of the roof and gutter covers, the inclinations of the roof and cover, the angle of repose of the debris, and the molecular attraction of the debris to the surfaces. It should be obvious, even to those not skilled in the art; that, for any given surface, any reduction in the inclination angle, that the surfaces makes with the horizontal, will yield a corresponding increase in debris retention. The pile-up of debris on the covers oriented at low angles to the horizontal eventually causing water to back-flow under shingles, or behind the fascia boards, to which the gutters are attached. Covers of much lower pitch than the inclined roof to which they are installed are particularly evident in the designs of Demartini(U.S. Pat. No. 4,497,146) and Heier (U.S. Pat. No. 2,873,700).
In addition to a pile-up of debris, experience has shown that horizontal slotted or screen gutter covers afford a potential trap for pine needles; the pine needles lodging in the vertical or near vertical end-wise in the slots, or appertures in the screens. This applies also to vertical screens such as that shown by Duffy in U.S. Pat. No. 4,493,588 in which a vertical screen (or nearly vertical screen) is used to block the flow of larger debris into the space between the curved cover and gutter. Debris, such as pine needles, lodging even in a vertical screen, are unsightly and labor-intensive to remove. The solid cover (Ref. Gutter Helmet) although smooth, is subject to debris build-up because of the characteristically low pitch compared to the roof from which water effluents are to be captured while debris is to be ejected.
A disadvantage of all designs is that each characteristically utilizes the wide-bottom gutter of conventional gutters that act as a settling basin for the flow rates typical of light rainfalls. This debris, in the form of particulates, such as grit or seeds and having a large surface-area-to-mass compared to sticks (for example) will follow the contour flow of water adhering to the underside of the curved section and discharging into the gutter which serves as a settling basin because of the low ratio of water mass flow rate compared to gutter width. Good in U.S. Pat. No. 4,406,093 shows a liner in a gutter that can be manually extracted from the gutter to periodically extract debris. Any large debris, such as a pine cone, acts as an obstruction to flow; and the higher the frequency of the debris, the greater the number of the discrete settling basins located serially along the gutter. The gutter of Good et al. U.S. Pat. No. 4,406,093 is equipped with a liner for the mechanical removal of debris. In addition to requiring frequent attention for the extraction of debris, the design does not address the problem of entrapment of small grits and seeds, a single large piece of debris partially blocking the flow creating a settling basin for small particles. The Good design becomes partially dis-functional, the extent of dis-functionality being functions of the debris rate and how often the debris is mechanically extracted.
The designs of Briggs and Duffy both feature curved covers having slopes equal to, but no less than the roof pitch, a desirable attribute inasmuch as the cover is no more a hindrance to the discharge of debris from the roof than the higher-coefficient-of-friction asphalt waterproofing materials most commonly used. However, both are used in conjuction with gutters having traditionally wide bottom dimensions that are conducive to settling-out the smaller debris that is not rejected by the curved covers by virtue of the much higher surface-tension-to-mass of the smaller debris.